ninja windows: fix wrappers not outputting with newlines
ninja windows: fix wrappers not outputting with newlines

splitlines strips newlines, and I wasn't readding them when writing to stdout.

R=thakis@chromium.org
BUG=chromium:122674

Review URL: https://chromiumcodereview.appspot.com/10068029
witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp